Retrospect 18.5.3 failed on a recycle backup, "... can not write session file" ArcDiskerror

[henry-in-florida]

One of my backups failed on doing a recycle backup, with the error. But it got worse from there: ALL of the drive contents got deleted! All the contents of the drive contained other Retrospect backups, so not just the one backup file, but all others were somehow deleted by this recycle action. I manually stopped the backup and checked the drive. The drive checked good in Disk Utility. No apparently failures. Just to be sure, I erased the drive and checked it. All OK. 

This is the log of the event:

 

+  Recycle backup using Bi-Weekly Mac Mini_Seagate 4TB12_3x at 6/6/22, 22:00:00 (Activity Thread 1)
    6/6/22 22:00:00: Finished scanning backup set data files
    To Backup Set MacMini_Seagate 4TB_12...
    6/6/22 22:00:00: Recycle backup: The Backup Set was reset
    Warning: volume Seagate 4TB_12 has the "Ignore ownership" setting enabled.
    -  6/6/22 22:00:00: Copying Seagate 4TB_12
    6/6/22 22:02:59: Found: 822960 files, 84614 folders, 3.1 TB
    6/6/22 22:03:01: Finished matching
    6/6/22 22:03:03: Selector "All Files" was used to select 822,960 files out of 822,960.
    6/6/22 22:03:06: Copying: 822960 files (3.1 TB) and 0 hard links
    6/6/22 22:03:08: Finished scanning backup set data files
    [*] ArcDisk::arcExportSessionFile: unexpected value of ArcCatalog::m_lastvol 0; can not write session file
    6/7/22 22:30:26: Execution stopped by operator
    Remaining: 822,960 files, 3.1 TB
    Completed: 0 files, 0 B
    Performance: 0 MB/minute
    Duration: 1:00:30:25 (1:00:29:57 idle/loading/preparing)

    [*] ArcDisk::arcExportSessionFile: unexpected value of ArcCatalog::m_lastvol 0; can not write session file

Recovery was simply to remake the catalog (same name and other parameters) and start over. Backup works for now. I am using an alternate backup application until/if this ever gets figured out. First time for this error for me. I've read about this error here in Windows applications. Including a screen shot of the current (restored) media set members as it completes the first repaired backup. 

Any ideas? 

Edited June 8, 2022 by henry-in-florida
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[Mayoff]

In 27 years of supporting Retrospect, I have never seen a recycle delete anything but the files that are inside the backup set that you are recycling. In the example screenshot above, the contents of 1-MacMini_Seagate 4TB_12, 2-MacMini_Seagate 4TB_12  and 3-MacMini_Seagate 4TB_12 should have been cleared out and nothing else. Those folders appear to be on 3 different disks.

The "ArcDisk::arcExportSessionFile: unexpected value of ArcCatalog::m_lastvol 0; can not write session file" error is a little odd and it implies that something prevented Retrospect from writing the .session file, but I have no way to know what caused that.  You may want to check the OS X Console utility logs to see if any unusual errors are reported for the time of the recycle operation. 

[henry-in-florida]

11 minutes ago, Mayoff said:

The "ArcDisk::arcExportSessionFile: unexpected value of ArcCatalog::m_lastvol 0; can not write session file" error is a little odd and it implies that something prevented Retrospect from writing the .session file, but I have no way to know what caused that.  You may want to check the OS X Console utility logs to see if any unusual errors are reported for the time of the recycle operation. 

Thanks for your suggestion, Robin. I'm just reporting what happened, just out of the blue with one of my media sets. The drive contained several other media sets. When I got to it to inspect what had happened, the whole device was completely empty. As described, started over. and the new backup on the reformatted device worked perfectly. 

Will research further as to what happened on Console logs. 

[henry-in-florida]

Robin,

There were no error logs recorded and visible in the console on that date. There was however a diagnostic error report on that date at midnight of 5JUN2022. Looks to me like it was a low disk space warning on the startup drive. I have since freed up space on that drive. How could this result in a disastrous failure of another entirely different operation using another attached drive and a running application? Why was an error in the Retrospect operation not logged? Guess we'll never know, the answer to these questions, either way. 

But please don't shoot the messenger. Thanks, I though you might want to know. 

Diagnostic Log_disk writes 20220606.rtf